The objectives of this research project are to study the chronic toxicity and carcinogenic effects of ten dyes and improve the quality of angiograms taken with these dyes. For this study it will be necessary to purify commercially available dyes, to remove toxic impurities, to improve the solubility and to increase the fluorescence efficiency and in some cases to modify the molecular structure of the dyes by sulfonation. Several Cyanine dyes will be tested for acute toxicity, and angiograms will be taken with these dyes in order to study the relationship that the fluorescence wavelength has in viewing different regions of the retina.